Correlation between cerebral oxygen metabolism and cerebral blood flow simultaneously measured before and after acetazolamide administration

The cerebral circulation and metabolism of ten preoperative cardiac surgery patients were assessed. Alterations in regional cerebral blood now (rCBF), measured by I-123-N-isopropyl-p-iodo-amphetamine single-photon emission co mputed tomography, and in cerebral oxygen metabolism, simultaneously detect ed by near-infrared spectroscopy (NIRS) before and after acetazolamide admi nistration, were investigated. The rCBF (ml/min/100 g) increased significan tly from 40.21+/-7.65 to 56.24+/-13.69 (p<0.001), and a significant increas e in oxyhemoglobin (Oxy-Hb) of 13.9% (p=0.0022) and total hemoglobin (Total -Hb) of 5.7% (0.0047) along with a significant decrease in deoxyhemoglobin (Deoxy-Hb) of 8.9% (p = 0.0414) were observed concomitantly. Thus, the Oxy- Hb/Total-Hb ratio (%Oxy-Hb) rose significantly from 67.26+/-9.82% to 72.98 +/-8.09% (p=0.0022). Examination of the relationships between individual pa rameters showed that the percentage changes in rCBF and Oxy-Hb were signifi cantly correlated (r=0.758, p=0.011). The percentage changes in rCBF and %O xy-Hb were also correlated significantly (r=0.740, p=0.014). In conclusion, this evidence suggested that NIRS is able to detect relative changes in ce rebral hemodynamics and reflect luxury perfusion induced by acetazolamide. (C) 1999 Society of Photo-Optical Instrumentation Engineers. [S1083-3668(99 )00904-1].